Glasses lens designing method, production method for glasses lens and computer program

Abstract

1 indicates the rotating point of the eyeball, 2 indicates the first eye position, 3 indicates the second eye position, and 4 indicates the third eye position. The lines indicated by thick lines at the respective eye positions are the horizontal meridian and vertical meridian (principal meridian) of the cornea. As is seen from the figure, the directions of the horizontal meridian and vertical meridian of the cornea at the third eye position 4, in particular, do not coincide with the directions of the horizontal meridian and vertical meridian at the first eye position 1. In the present means, in order to perform aberration correction of the ophthalmic lens not only in the first eye position and second eye position but also in the third eye position under conditions that are suited to the prescription of the user and conditions of use, the prescription surface is made aspherical while taking into account the astigmatic axis of the eye at arbitrary eye positions in accordance with the laws of Donders-Listing. As a result, the prescription surface can be designed so that favorable optical characteristics can be obtained in the case of various specifications involving individual information such as the prescription of the ophthalmic lens user.

Description

TECHNICAL FIELD [0001] The present invention relates to an ophthalmic lens design method, an ophthalmic lens manufacturing method, and a computer program used in ophthalmic lens design. BACKGROUND ART [0002] Generally, the relationship between the apical curvature of an ophthalmic lens at which the astigmatic aberration of the light rays passing through the lens shows a minimum value and the apical refractive power on the optical axis of the lens (hereafter referred to as the “dioptric power”) can be obtained, for example, from the Tscherning ellipse. [0003] Specifically, it is well known that the occurrence of astigmatic aberration in the peripheral parts of the lens can be suppressed by adjusting the curvatures of both refractive surfaces of the lens to an optimal combination obtained by means of this Tscherning ellipse, and the optical performance drops conspicuously if a combination of curvatures of both refractive surfaces that departs greatly from this Tscherning ellipse is se...

AI Technical Summary

Benefits of technology

[0022] In the present means, the shape of the refractive surface whose shape is not formed beforehand is designed in accordance with such laws of Donders-Listing so that this is an aspherical surface shape that corrects the aberration of the ophthalmic lens in accordance with at least the refractive power that is necessary for refractive correction of the user or the refractive power that is necessary for astigmatic correction of the user, or both. Accordingly, correction of the aberration of the ophthalmic lens at the third eye position, in particular, is appropriately performed, so that an ophthalmic lens that has favorable optical performance overall can be designed.

[0055] In the present means, the design data is transmitted via communication means; accordingly, in cases where the manufacturer and designer are in mutually remote locations, e.g., in cases where the manufacturer and designer are firms in different countries, manufacture can be performed especially efficiently. Arbitrary means such as inter-computer communications by wire and facsimile can be used as communication means.

Problems solved by technology

Specifically, in cases where problems of optical performance and external appearance are taken into account, the practical range of the base curve of an ophthalmic lens is limited to a specified range in accordance with the dioptric power of the ophthalmic lens.

Furthermore, in cases where the refractive surfaces are constructed only from spherical surfaces, it is impossible to solve the problems of maintaining the optical performance in the desired range and improving the external appearance at the same time.

If this set dioptric power is taken as the standard dioptric power for this semi-finished lens, then the optical performance of the lens in the dioptric power range in the vicinity of this standard dioptric power is favorable; however, in a dioptric power range that is removed from this standard dioptric power, a deterioration in the optical performance especially in the peripheral parts of the lens cannot be avoided.

Furthermore, the following drawback is also encountered: namely, in cases where correction of astigmatism is necessary, even if the dioptric power is the standard dioptric power, a deterioration in the optical performance in the peripheral parts of the lens cannot be avoided.

In order to provide an ophthalmic lens that is optimal for the individual user in accordance with specifications and conditions of use that vary with each user, the mere evaluation of the optical performance according to the meridional image plane and sagittal image plane, astigmatic aberration and mean refractive power conventionally used in the design of ophthalmic lenses is insufficient.

However, a so-called trade-off relationship may exist among different types of optical performance; consequently, it is difficult to reduce all aberration to a minimum value.

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